Hydraulic system having diagnostic mode of operation

ABSTRACT

A hydraulic system is disclosed for use with. a machine. The hydraulic system may have an actuator, a valve associated with the actuator, at least one sensor configured to generate signals indicative of performance parameters of the hydraulic system, and a controller. The controller may be configured to determine at least one of a diagnostic movement and position of at least one of the fluid actuator and valve required to perform a health cheek, and to correlate the signals generated only during completion of the diagnostic movement or only when the at least one of the fluid actuator and valve are in the diagnostic position to values of the performance parameters. The controller may also be configured to make a comparison of the values of the performance parameters to expected values, and to determine a health of the hydraulic system based on the comparison.

TECHNICAL FIELD

The present disclosure relates generally to a hydraulic system and, moreparticularly, to a hydraulic system having a diagnostic mode ofoperation.

BACKGROUND

Hydraulically operated machines, such as excavators, loaders, dozers,motor graders, and other types of heavy equipment, have multipleactuators (e.g., cylinders, motors, fans, brakes, etc.) connected tomove the machines. High-pressure fluid is directed from one or morepumps on each machine to the actuators via corresponding valves. Each ofthe pumps, actuators, valves, and associated conduits and seals can wearover time and/or be damaged by operation of the machine within itsnormal environment. When these components wear or are damaged, operationof the machine degrades, For example, the machines may operate with lesspower, less speed, less range of motion, lower efficiency, lessstability, and/or less control when the hydraulic components are worn ordamaged. In addition, excessive wearing of one hydraulic component(e.g., a pump) could result in catastrophic damage to the remaininghydraulic components, if the wear is not addressed in a timely manner.For this reason, it can be important to monitor a health of thecomponents and quickly address any component issues in order to maintainthe machines at a desired operating level.

Historically, hydraulic component health was monitored manually duringperiodic or as-needed checks by a technician. In particular, at aparticular service interval or when malfunction of a particularcomponent was suspected, the technician would have been called out tovisit a particular machine. During the visit, the technician. wouldconnect one or more sensors to suspected circuits of the machine,monitor parameters (e.g., pressure, speed, range of motion, etc.) duringparticular movements of the machine, and then compare the monitoredparameters to threshold ranges or values. If a significant deviationbetween the monitored and threshold parameter values existed, it couldbe concluded that a component was worn or damaged and was in need ofrepair.

Although perhaps acceptable in some situations, the historical method ofcomponent health monitoring may also be problematic. In particular, itmay be difficult and time consuming for the technician to know whatsensors are appropriate to use in a particular situation, and for thetechnician to properly connect the sensors at the correct locationswithin the suspect circuit. In addition, the technician may be requiredto know the appropriate conditions under which parameter monitoringshould be performed (e.g., temperature, machine kinematics andpositions, movement speeds and loads, etc.), and to know thecorresponding expected performance ranges or threshold values. Thetechnician may then be required to perform comparison calculations andto judge a severity of a resulting deviation, which can be subject tothe technician's training and experience, the machine's age andenvironment, and other similar factors. Accordingly, the historicalprocess may be slow and expensive, and provide opportunity for error.

One attempt to address the issues discussed above is disclosed in U.S.Pat. No. 7,204,138 (the '138 patent) by Du that issued on Apr. 17, 2007.In particular, the '138 patent discloses a health indicator for ahydraulic system having a pump, a sump, a cylinder, and a valveconnecting the cylinder to the pump and the sump. The health indicatorincludes a pump discharge pressure sensor, a swashplate angle sensor, apump speed sensor, a head-end pressure/position/speed sensor, a rod-endpressure/position/speed sensor, and a controller. The controller isconfigured to compute, based on signals received from the sensors inreal time during normal operation, an effective bulk modulus of thepump, aeration of the hydraulic system, and/or a cavitation condition ofthe pump. The controller is further configured to compare the effectivebulk module, aeration, and/or cavitation condition to predeterminedconditions stored within a health database. From this comparison, thecontroller determines a relative operating health of the hydraulicsystem. Based on the relative operating health of the hydraulic system,maintenance operations and repairs can be made to prevent catastrophicfailure or before substantial deterioration of the system can occur.

Although the health indicator of the '138 patent may be helpful indetermining when a pump malfunction exists, it may be limited. Inparticular, the health indicator may do little to determine when anon-pump malfunction exists. In addition, there may be times whenmachine conditions are unfavorable for health checking, and the healthindicator of the '138 patent may be unable to account for these times.Further, the health indicator may provide only an indication as toproper or improper pump operation, which may still require somesubjective judgment from the technician regarding how to address theoperation.

The disclosed hydraulic system is directed to overcoming one or more ofthe problems set forth above and/or other problems of the prior art.

SUMMARY

One aspect of the present disclosure is directed to a hydraulic system.The hydraulic system may include a fluid actuator, a valve associatedwith the fluid actuator, at least one sensor configured to generate asignal indicative of a performance parameter of the hydraulic system,and a controller in communication with the at least one sensor. Thecontroller may be configured to determine at least one of a diagnosticmovement and a diagnostic position of at least one of the fluid actuatorand the valve required to perform a health check of the hydraulicsystem, and to correlate the signal generated only during completion ofthe diagnostic movement or only when the at least one of the fluidactuator and the valve are in the diagnostic position to a value of theperformance parameter. The controller may also be configured to make acomparison of the value of the performance parameter to an expectedvalue, and to determine a health of the hydraulic system based on thecomparison.

Another aspect of the present disclosure is directed to a method ofdetermining a health of a hydraulic system having an actuator and avalve associated with the actuator. The method may include generating asignal indicative of a performance parameter of the hydraulic system,and determining at least one of a diagnostic movement and a diagnosticposition of at least one of the fluid actuator and the valve requiredfor diagnosing the health of the hydraulic system. The method may alsoinclude correlating the signal generated only during completion of thediagnostic movement or only when the at least one of the fluid actuatorand the valve are in the diagnostic position to a value of theperformance parameter. The method may further include making acomparison of the value of the performance parameter to an expectedvalue, and determining the health of the hydraulic system based on thecomparison.

Yet another aspect of the present disclosure is directed to a machine.The machine may include a frame, a power source mounted to the frame, alinkage arrangement, and an actuator configured to move the linkagearrangement. The machine may also include a pump, a sump, and a valvedisposed between the actuator, the pump, and the sump. The machine mayfurther include a plurality of sensors configured to generate signalsindicative of performance parameters of the machine, and a controller incommunication with the plurality of sensors. The controller may beconfigured to receive input indicative of a suspected hydrauliccomponent malfunction, and to determine at least one of a diagnosticmovement and a diagnostic position of at least one of the fluid actuatorand the valve required to perform a health check of the machine based onthe suspected hydraulic component malfunction. The controller may alsobe configured to correlate the signals generated only during completionof the diagnostic movement or only when the at least one of the fluidactuator and the valve are in the diagnostic position to values of theperformance parameters. The controller may further be configured todetermine an age of the machine, to make an age-adjusted comparison ofthe values of the performance parameters to expected values, and todetermine a health of the machine based on the age-adjusted comparison.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic illustration of an exemplary disclosed machinein a working environment;

FIG. 2 is a schematic illustration of an exemplary disclosed hydraulicsystem associated with the machine of FIG. 1;

FIG. 3 is a schematic illustration of an exemplary disclosed controlvalve that may be used in conjunction with the hydraulic system of FIG.2; and

FIGS. 4, 5, and 6 are flowcharts illustrating exemplary disclosedprocesses that may be performed by the hydraulic system of FIG. 2.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary machine 10 having multiple systems andcomponents that cooperate to excavate and load earthen material onto anearby haul vehicle 12. In the depicted example, machine 10 is ahydraulic excavator. It is contemplated, however, that machine 10 couldalternatively embody another type of excavation or material handlingmachine, such as a backhoe, front shovel, shovel, a motor grader, adozer, or another similar machine. Machine 10 may include, among otherthings, a linkage 14 configured to move a work tool 16 between a diglocation 18 within a trench or at a pile, and a dump location 20, forexample over haul vehicle 12 during a well-known truck loading cycle.Machine 10 may also include an operator station 22 for manual control oflinkage 14. It is contemplated that machine 10 may perform both cyclicaland non-cyclical operations, including cyclical operations other thantruck loading, if desired.

Linkage 14 may include a plurality of structural links that are pinnedto fluid actuators, which generate movements of work tool 16. In thedisclosed example, linkage 14 includes a boom 24 that is verticallypivoted relative to a machine frame 26 by one or more boom cylinders 28(only one shown in FIG. 1), and a stick 30 that is vertically pivotedrelative to boom 24 by a stick cylinder 32. Linkage 14 further includesa bucket cylinder 34 that operatively connects work tool 16 to a distalend of stick 30 for use in racking and dumping (i.e., curling) work tool16. Frame 26 may be pivotally connected to an undercarriage 36 by aswing motor 38, such that frame 26, linkage 14, and work tool 16 may beswung together in a horizontal direction. It is contemplated that agreater or lesser number of fluid actuators may be connected withlinkage 14 and/or connected in a manner other than described above, ifdesired.

Operator station 22 may be configured to receive input from an operatorindicative of a desired work tool and/or machine movement. Specifically,operator station 22 may include one or more interface devices 40 locatednear an operator seat (not shown). In one example, interface devices 40are embodied as proportional-type controllers configured to positionand/or orient work tool 16 or undercarriage 36 by producing positionsignals indicative of a desired actuator speeds and/or forces inparticular directions. The position signals may be used to actuate anyone or more of cylinders 28, 32, 34 and/or swing motor 38.

It is contemplated that different interface devices 40 may alternativelyor additionally be included within operator station 22. These devicesmay include, for example, wheels, knobs, push-pull devices, switches,pedals, touchscreen monitors, and other devices known in the art. Thedevices may be used to selectively activate a mode of operation (e.g.,an autonomous control mode), to initiate a function (e.g., a healthchecking function), and/or to receive training (e.g., to receiveinstructions and/or recommendations).

As illustrated in FIG. 2, machine 10 may include a hydraulic system 42having a plurality of fluid components that cooperate to move work tool16 (referring to FIG. 1) and machine 10. In particular, hydraulic system42 may include a first circuit 44 configured to receive a first streamof pressurized fluid from a first source 46, and a second circuit 48configured to receive a second stream of pressurized fluid from a secondsource 50. First circuit 44 may include a boom control valve 54, abucket control valve 56, and a left travel control valve 58 connected toreceive the first stream of pressurized fluid in parallel. Secondcircuit 48 may include a right travel control valve 60, a stick controlvalve 62, and a swing control valve 63 connected in parallel to receivethe second stream of pressurized fluid. It is contemplated thatadditional control valve mechanisms may be included within first and/orsecond circuits 44, 48 such as, for example, one or more attachmentcontrol valves and other suitable control valve mechanisms.

The control valves of first and second circuits 44, 48 may be connectedto allow pressurized fluid to flow to and drain from their respectiveactuators via common passageways. Specifically, the control valves offirst circuit 44 may be connected to first source 46 by way of a firstcommon supply passageway 66, and to a tank 64 by way of a first commondrain passageway 68. The control valves of second circuit 48 may beconnected to second source 50 by way of a second common supplypassageway 70, and to tank 64 by way of a second common drain passageway72.

Because the elements of boom, bucket, left travel, right travel, stick,and swing control valves 54, 56, 58, 60, 62, 63 may be similar andfunction in a related manner, only the operation of bucket control valve56 will be discussed in this disclosure. As shown in FIG. 3, bucketcontrol valve 56 may include a first chamber supply element 56A, a firstchamber drain element 56C, a second chamber supply element 56B, and asecond chamber drain element 56D. First and second chamber supplyelements 56A, 56B may be connected in parallel with fluid passageway 66to fill their respective chambers with fluid from first source 46, whilefirst and second chamber drain elements 56C, 56D may be connected inparallel with fluid passageway 68 to drain the respective chambers offluid.

To retract bucket cylinder 34, first chamber supply element 56A may bemoved to allow the pressurized fluid from first source 46 to fill thefirst chamber of bucket cylinder 34 with pressurized fluid via fluidpassageway 66, while second chamber drain element 56D may be moved todrain fluid from the second chamber of bucket cylinder 34 to tank 64 viafluid passageway 68. To extend bucket cylinder 34, second chamber supplyelement 56B may be moved to fill the second chamber of bucket cylinder34 with pressurized fluid, while first chamber drain element 56C may bemoved to drain fluid from the first chamber of bucket cylinder 34. Insome instances, it may also be possible to pass pressurized fluiddirectly from passage 66 to passage 68 via control valve 54, if desired(e.g., from 56A to 56C or from 56B to 56D), such that no movement ofbucket cylinder 34 is realized. This may be done, for example, during adiagnostic routine. it is contemplated that both the supply and drainfunctions may alternatively be performed by a single element associatedwith the first chamber and a single element associated with the secondchamber, or by a single valve that controls all filling and drainingfunctions.

Returning to FIG. 2, the common supply and drain passageways of firstand second circuits 44, 48 may be interconnected for makeup and relieffunctions. In particular, first and second common supply passageways 66,70 may receive makeup fluid from tank 64 by way of first and secondbypass elements 74, 76, respectively fluid within first or secondcircuits 44, 48 exceeds a predetermined pressure level, fluid from thecircuit having the excessive pressure may drain to tank 64 by way of ashuttle valve 78 and a common main relief element 80. Other arrangementsof bypass and relief valves may be used, as is known in the art.

A straight travel valve 82 may selectively rearrange left and righttravel control valves 58, 60 into a parallel relationship with eachother. In particular, straight travel valve 82 may include elementsmovable from a first position at which left and right travel controlvalves 58, 60 are independently supplied with pressurized fluid, to asecond position at which left and right travel control valves 58, 60 areinterconnected for dependent movement. The dependent movement of leftand right travel motors 65L, 65R may function to provide substantiallyequal rotational speeds of left and right tracks 40L, 40R, therebypropelling machine 10 in a straight direction.

A combiner valve 84 may be used to selectively combine the first andsecond streams of pressurized fluid from first and second common supplypassageways 66, 70 for high speed movement of one or more fluidactuators. In particular, when a particular combination of functionsassociated with a particular circuit requires a rate of fluid flowgreater than an output capacity of the associated single fluid source,fluid from the other circuit may be diverted to supply the requiredextra flow.

In one embodiment, hydraulic system 42 may include a warm-up circuit.That is, the common supply and drain passageways 66, 68 and 70, 72 offirst and second circuits 44, 48, respectively, may be selectivelycommunicated via first and second bypass passageways 86, 88 for warm-upand/or other bypass functions. A bypass valve 90 may be located in eachof bypass passageways 86, 88 and configured to direct fluid from commonsupply passageways 66 and 70 to common drain passageways 68 and 72,respectively. It is contemplated that bypass passageways 86, 88 andbypass valves 90 may be omitted, if desired.

Hydraulic system 42 may also include a controller 92 in communicationwith operator interface device 40, first and/or second sources 46, 50,the supply and drain elements of control valves 54-62, combiner valve84, and bypass valves 90. It is contemplated that controller 92 may alsobe in communication with other components of hydraulic system 42 suchas, for example, first and second bypass elements 74, 76, common mainrelief element 80, straight travel valve 82, and other such componentsof hydraulic system 42. Controller 92 may embody a singlemicrocontroller or multiple microcontrollers that include a means forcontrolling an operation of hydraulic system 42. Numerous commerciallyavailable microcontrollers can be configured to perform the functions ofcontroller 92. It should be appreciated that controller 92 could readilybe embodied in a general machine microcontroller capable of controllingnumerous machine functions. Controller 92 may include a memory, asecondary storage device, a controller, and any other components forrunning an application. Various other circuits may be associated withcontroller 92 such as power supply circuitry, signal conditioningcircuitry, solenoid driver circuitry, and other types of circuitry.

One or more maps relating the interface device position signal, actuatorvelocity, associated flow rates and pressures, and/or valve element andactuator positions may be stored in the memory of controller 92. Each ofthese maps may include a collection of data in the form of tables,graphs, and/or equations. Controller 92 may be configured to allow theoperator to directly modify these maps and/or to select specific mapsfrom available relationship maps stored in the memory of controller 92to affect fluid actuator motion. It is contemplated that the maps mayadditionally or alternatively be automatically selectable based onactive modes of machine operation.

In some embodiments, the maps stored in the memory of controller 92 maybe modified or adjusted by controller 92 based on an age and/orcondition of machine 10 and hydraulic system 42. That is, as machine 10and hydraulic system 42 age, the relationships between pressures,velocities, flow rates, positions, and cycle times may change naturallydue to expected wear of system components. If unaccounted for, the samecombination of commands that initially resulted in a desired pressure,velocity, flow rate, position, cycle time, etc., may instead result insomething unexpected and/or undesired. Accordingly, controller 92 may beconfigured to selectively adjust the values stored in the maps byamounts relating to the age of machine 10 and/or hydraulic system 42.

Controller 92 may be configured to receive input from operator interfacedevice 40 and to command operation of control valves 54, 56, 58, 60, 62,63 in response to the input and the relationship maps described above.Specifically, controller 92 may receive an interface device positionsignal indicative of a desired velocity of a particular actuator, andreference the selected and/or modified relationship maps stored in thememory of controller 92 to determine operating parameters for each ofthe corresponding supply and drain elements within control valves 54,56, 58, 60, 62, 63. The operating conditions may then be commanded ofthe appropriate supply and drain elements to cause filling of the firstor second chambers at a rate that results in the desired work toolmovement, position, velocity, and/or force.

When a malfunction of a particular hydraulic system component occurs,fluid flow through hydraulic system 42 may be disrupted, This disruptionmay be manifest in a number of ways. For instance, one or more actuatorsand/or valves may move at a speed and/or with a force different thandesired or move discontinuously. Resulting pressures, pressuredifferentials, flow rates, etc. may be lower or higher than normal.Desired positions of the valves and/or actuators may not be achieved.Other unexpected results may also occur. Accordingly, it can beimportant for the health of hydraulic system 42 to be periodicallychecked, such that performance of machine 10 may be continuous andreliable. Controller 92 may facilitate these checks by implementing oneor more different diagnostic routines, as will be described in moredetail below.

In some embodiments, controller 92 may communicate with the operator ofmachine 10 (e.g., via interface devices 40) to instruct the operator tomanually cause movements and/or velocities of particular hydraulicsystem components that are conducive to the diagnostic routinesperformed by controller 92 during the health check of hydraulic system42. For example, during the health check of system 42, controller 92 maybe configured to reference one or more of the maps stored in the memoryof controller 92 to determine particular positions and/or velocitiesthat should be implemented during a particular one of the diagnosticroutines. Controller 92 may then cause corresponding instructions to beshown on a display inside operator station 22, allowing the operator tomanually implement the diagnostic positions and/or velocities.Controller 92 may also be configured, in other embodiments, toautonomously cause the particular diagnostic movements and velocities tobe implemented, if desired. In yet other embodiments, controller 92 maysimply be configured to recognize when the particular diagnosticmovements and velocities are occurring naturally during normaloperations of machine 10, and then responsively implement the associateddiagnostic routines. These processes will be discussed in more detail inthe following section, with reference to FIGS. 4-6.

Controller 92 may be configured to monitor the performance of hydraulicsystem 42 during completion of the diagnostic routines, for example byway of one or more sensors 94. These performance parameters may include,among other things, a time required to complete a particular known cycle(e.g., the truck loading cycle), a position and/or speed of a particularcontrol valve or actuator, a pressure and/or pressure differential at aparticular location within system 42, a pump displacement setting, anengine speed, etc. Controller 92 may then compare the monitoredperformance to age-adjusted expected values or ranges for the sameparameters to determine if particular components of hydraulic system 42are functioning properly.

In the disclosed embodiments of FIGS. 2 and 3, multiple pressure-typesensors 94 are shown. In particular, a first pressure sensor 94 islocated to sense a pressure of common supply passage 66 (e.g., an outletpressure of first source 46), while a second pressure sensor 94 islocated to sense a pressure of common drain passage 68. In this manner,controller 92 may be able to calculate a pressure differential acrossany one or more of hydraulic cylinders 28, 32 and left travel motor 65L(depending on which actuator is being used at the time of signalgeneration) based on signals from the first and second pressure sensors94. Similarly, a third pressure sensor 94 is located to sense a pressureof common supply passage 70 (e.g., an outlet pressure of second source50), while a fourth pressure sensor 94 is located to sense a pressure ofcommon drain passage 72. In this manner, controller 92 may be able tocalculate a pressure differential across any one or more of right travelmotor 65R, hydraulic cylinder 34, or swing motor 38 based on signalsfrom the first and second pressure sensors 94. Likewise, one or morepressure sensors 94 may be associated with some or all of control valves54, 56, 58, 60, 62, 63 (see FIG. 3) or any other valve (e.g., bypassvalves 74, 76, main relief valve 80, straight travel valve 82, combinervalve 84, etc.) for similar purposes. It is contemplated that any numberof sensors of any type may be utilized and/or placed at differentlocations within hydraulic system 42, as desired.

FIGS. 4-6 are flowcharts depicting exemplary diagnostic operations ofhydraulic system 42. FIGS. 4-6 will be discussed in more detail in thefollowing section to further clarify the disclosed concepts.

INDUSTRIAL APPLICABILITY

The disclosed hydraulic system may be applicable to any machine havingfluid components. The disclosed hydraulic system may help to maintaindesired operation of the machine through implementation of health checksof the components. The disclosed hydraulic system may also help todiagnose a problem with the components via one or more differentdiagnostic routines (e.g., a manually triggered routine, anautomatically triggered routine, and a continuously operating routine).These routines will now be described in detail with reference to FIGS.4-6.

The manually triggered routine is shown in FIG. 4. As shown in thisfigure, the first step of the diagnostic routine may be for controller92 to receive input from the operator of machine 10 that is indicativeof a desire to start a diagnostic check of hydraulic system 42 (Step400). This input may be generated via manipulation of interface device40. For example, the operator of machine 10 may manipulate interfacedevice 40 at the start of a shift, at the end of a shift, during anormal maintenance process, when a problem with hydraulic system 42 issuspected, or at any other convenient time.

Once the input from the operator is received, controller 92 maydetermine if the current operating parameters of machine 10 are withinranges necessary for accurate diagnostic testing to begin (Step 405). Inparticular, in some embodiments, controller 92 may be able to accuratelycheck the health of machine 10 only when particular circumstances arepresent. These circumstances can be associated with, among other things,a particular position, orientation, or movement of a particular valve oractuator; a particular pattern or sequence of movements (e.g.,completion of a cycle such as the truck loading cycle), a particularspeed of movement; movement under a particular load; movement whenhydraulic temperatures and/or pressures are at certain levels; etc. Insome embodiments, health checks of different hydraulic system componentsmay require different circumstances to be present, in other embodiments,a circuit-level health check may require the circumstances to change ina particular order and at particular timings, as controller 92sequentially checks each component within a particular circuit.

Accordingly, depending on the type of diagnostic check that has beenrequested by the operator, controller 92 may be configured to referencethe type of diagnostic check with the maps stored in memory to determinea corresponding circumstance or set of circumstances that should bepresent during the diagnostic check to produce accurate results.Controller 92 may then instruct the operator of machine 10 to changemachine operating parameters to provide the correct set of circumstances(Step 410). For example, controller 92 may cause to he displayed withinoperator station 22 images, written instructions, and/or verbalinstructions telling the operator to raise boom 24 (referring to FIG. 1)to a particular height, at a particular speed, with a particular load,or within a particular period of time; to complete a truck loadingcycle; to rack work tool 16; to swing frame 26, etc. In some instances,the instructions may pertain to the simultaneous use of multiple valvesand/or actuators. In other instances, however, the instructions maypertain to the independent use of a single valve and/or actuator. Byusing only a single valve and/or actuator at a time during diagnosticchecking, a number of factors influencing hydraulic system performancemay be reduced, and the remaining factors may be associated with onlythe particular valve or actuator being used. In this way, a component orcircuit suspected of malfunctioning or failing may be independentlytested.

During and/or after operator-caused movements of machine 10 that producethe circumstances required the operator-requested diagnostic check,controller 92 may sense the performance of machine 10 (Step 415). Forexample, while work tool 16 is being lifted to a particular height (orlifted at a particular velocity, under a particular load, duringcompletion of a particular cycle, etc.) controller 92 may monitorsignals (e.g., pressure or pressure differential signals) produced byone or more sensors 94 associated with one or more of the hydraulicsystem components (e.g, boom control valve 54, boom cylinders 28, firstsource 46, etc.) being used to do the lifting.

After completion of step 415, controller 92 may be further configured tocompare the values of the signals sensed during step 415 tocorresponding expected values or ranges to determine if the values arewithin acceptable tolerances of the expected performance values orranges (Step 420). For example, controller 92 may compare the pressuredifferential monitored when lifting work tool 16 during completion ofstep 415 to an expected pressure differential value or range. Theexpected performance value and/or range may be stored within the memoryof controller 92 for this purpose.

When the comparison made by controller 92 at step 420 shows that themonitored performance of machine 10 is not within an acceptabletolerance of the expected performance value or range, controller 92 maydetermine a deviation level associated with the results of thecomparison (Step 425). In one example, controller 92 is configured toclassify a deviation determined at step 420 as a Level I deviation, aLevel II deviation, or a Level III deviation. In this example, a LevelIII deviation may be the most severe deviation possible and oftencorresponds with a significant failure of hydraulic system 42. Inresponse to a deviation being classified as Level III, controller 92 mayinstruct the operator to immediately shut down machine 10 in order toprevent further damage of hydraulic system components (Step 430).Controller 92 may provide additional information to the operatorregarding the failure, along with recommendations about what repairsshould be performed.

A Level II deviation may be less severe than a Level III deviation, butstill could result in costly damage to or downtime of machine 10 if notcorrected in a timely manner. Accordingly, in response to a deviationbeing classified as Level II, controller 92 may instruct the operator tocomplete the current work shift (operation, task, etc.) and then, at aconvenient time, to move machine 10 to a repair facility for service tobe performed (Step 435). This may allow for the service to be performedat a time when the production of machine 10 will not be significantlyimpacted, and machine 10 may not be left stranded at a locationinconvenient for the repairs to be made. As with a Level III deviation,controller 92 may provide additional information regarding the cause ofthe Level II deviation, along with recommendations about what repairsshould be performed.

A Level I deviation may be less severe than a Level II deviation, butstill have a long-term effect on the operating cost and/or profitabilityof machine 10, if not corrected. Accordingly, in response to a deviationbeing classified as Level I, controller 92 may recommend to the operatorthat a specific repair be performed at a next scheduled service interval(Step 440).

Returning to step 420, when machine 10 performs as expected (step 420:Y)and passes the diagnostic health check, controller 92 may complete theprocess without flagging any kind of failure or repair error (Step 445).This result may be reported to the operator of machine 10, and controlmay return to step 400.

The automatically triggered routine is shown in FIG. 5. As shown in thisfigure, the first step of the diagnostic routine may be for controller92 to receive input that is indicative of a possible malfunction ofhydraulic system 42 (Step 500). This input may be generated any time thevalue of a monitored performance parameter falls outside of an expectedrange. For example, when a temperature, pressure, cycle time, etc.generated by one or more sensors 94 is too high, too low, or outside ofan expected range for an extended period of time, it may be possible fora failure to be the cause. In this situation, controller 92 may beautomatically triggered to start a diagnostic routine in order todetermine the source of the failure.

Once controller 92 is triggered to initiate a diagnostic routine,controller 92 may determine what diagnostic checks are associated withthe possible malfunction (Step 505). In particular, controller 92 may becapable of performing may different diagnostic checks; each associatedwith a different component and/or circuit. Rather than performing all ofthe diagnostic checks in response to any sensed abnormality, controller92 may instead narrow down the different diagnostic checks to a subsetof checks associated with the particular component or circuit that issuspected of malfunctioning. In this way, a time and cost of thediagnostic checking may be reduced. Controller 92 may reference theabnormal value(s) used as triggers for step 500 with the maps stored inmemory to determine the corresponding set of diagnostic checks.

As described above, controller 92 may then determine if the currentoperating parameters of machine 10 are within accuracy ranges necessaryfor testing of the subset of diagnostic checks to begin (Step 510). Inparticular, in some embodiments, controller 92 may be able to accuratelycheck the health of machine 10 only when particular circumstances arepresent. These circumstances can be associated with, among other things,a particular position, orientation, or movement of a particular valve oractuator; a particular pattern or sequence of movements (e.g.,completion of a cycle such as the truck loading cycle), a particularspeed of movement; movement under a particular load; movement Whenhydraulic temperatures and/or pressures are at certain levels; etc. Insome embodiments, health checks of different hydraulic system componentsmay require different circumstances to be present. In other embodiments,a circuit-level health check may require the circumstances to change ina particular order and at particular timings, as controller 92sequentially checks each component within a particular circuit.

Accordingly, depending on the type of diagnostic check that will beperformed, controller 92 may be configured to reference the type ofdiagnostic check with the maps stored in memory to determine acorresponding circumstance or set of circumstances that should bepresent during the diagnostic check to produce accurate results. Andwhen the current machine parameters do not match the parameters requiredfor diagnostic testing, controller 92 may automatically make changes tomachine operating parameters to provide the correct set of circumstances(Step 515). For example, controller 92 may automatically raise boom 24(referring to FIG. 1) to a particular height, at a particular speed,with a particular load, or within a particular period of time; tocomplete a truck loading cycle; to rack work tool 16; to swing frame 26,etc. in some instances, the movements may be simultaneously commanded ofmultiple valves and/or actuators. In other instances, however, themovements may he commanded of a single valve and/or actuator.

During and/or after the autonomous movements of machine 10 that producethe circumstances required for the subset of diagnostic checks,controller 92 may sense the performance of machine 10 (Step 520). Forexample, while controller 92 is causing work tool 16 to be lifted to aparticular height (or lifted at a particular velocity, under aparticular load, during completion of a particular cycle, etc.,)controller 92 may monitor signals (e.g., pressure or pressuredifferential signals) produced by one or more sensors 94 associated withone or more of the hydraulic system components (e.g., boom control valve54, boom cylinders 28, first source 46, etc.) being used to do thelifting.

After completion of step 520, controller 92 may be further configured tocompare the values of the signals sensed during step 520 tocorresponding expected values or ranges to determine if the values arewithin acceptable tolerances of the expected performance values orranges (Step 525). For example, controller 92 may compare the pressuredifferential monitored when lifting work tool 16 during completion ofstep 520 to an expected pressure differential value or range. Theexpected performance value and/or range may be stored within the memoryof controller 92 for this purpose.

When the comparison made by controller 92 at step 525 shows that themonitored performance of machine 10 is not within an acceptabletolerance of the expected performance value or range, controller 92 maydetermine a deviation level associated with the results of thecomparison (Step 530). As described above with respect to the manualmode of operation, controller 92 may also be configured to classify adeviation determined at step 525 during operation in the automatic modeas the Level I deviation, the Level II deviation, or the Level IIIdeviation. In response to a deviation being classified as Level III,controller 92 may automatically shut down machine 10 in a safe andcontrolled manner in order to prevent further damage of hydraulic systemcomponents (Step 535). Controller 92 may then communicate (e.g., to anonboard operator or to a remote back office) additional informationregarding the failure, along with recommendations about what repairsshould be performed.

In response to a deviation being classified as Level II, controller 92may autonomously move machine 10 to a repair facility for service to beperformed at completion of the current work shift (operation, task,etc.) (Step 540). This may allow for the service to he performed at atime when the production of machine 10 will not be significantlyimpacted, and machine 10 may not be left stranded at a locationinconvenient for the repairs to be performed. As with a Level IIIdeviation, controller 92 may provide additional information regardingthe cause of the Level II deviation, along with recommendations aboutwhat repairs should be performed.

In response to a deviation being classified as Level I, controller 92may automatically schedule a specific repair to be completed at a nextscheduled service interval (Step 545).

Returning to step 525, when machine 10 performs as expected (step 525:Y)and passes the diagnostic health check, controller 92 may complete theprocess without flagging any kind of failure or repair error (Step 550).

The continuous mode of operation shown in FIG. 6 may not require aspecific trigger in order to initiate diagnostic testing, other thanmachine 10 being turned on (Step 600). In particular, any time thatmachine 10 is operational, controller 92 may be continuously determiningif the current operating parameters of machine 10 are within accuracyranges necessary for completing any one of a plurality of diagnostictests that controller 92 is capable of performing (Step 605). Asdescribed above, in some embodiments, controller 92 may be able toaccurately perform certain diagnostic checks only when particularcircumstances are present. Accordingly, depending on the currentconditions, controller 92 may begin a particular diagnostic check andstart sensing corresponding performance parameters any time that theassociated circumstances are present (Step 610). For example, any timethat boom 24 is being lifted at a particular speed, with a particularload, to a particular height, etc., without any simultaneous tilting,racking, or swinging, controller 92 may be configured to initiate adiagnostic check of boom control valve 54 and/or boom cylinders 28.Controller 92 may then complete steps 615-640, which may besubstantially identical to steps 420 445 already described above.

Several benefits may be associated with the disclosed hydraulic system.For example, the disclosed hydraulic system may be configured todiagnose malfunctions associated with any hydraulic system component,including pump and non-pump components. In addition, a high degree ofaccuracy may be obtained during diagnostic checks, as initiation of thediagnostic checks may be based on current operating conditions beingfavorable for the checks. Further, the disclosed hydraulic system mayprovide not only an indication of a source of a system failure, but mayalso provide instructions on how to respond to the failure.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the disclosed hydraulicsystem. Other embodiments will be apparent to those skilled in the artfrom consideration of the specification and practice of the disclosedhydraulic system. It is intended that the specification and examples beconsidered as exemplary only, with a true scope being indicated by thefollowing claims and their equivalents.

What is claimed is:
 1. A hydraulic system, comprising: a fluid actuator;a valve associated with the fluid actuator; at least one sensorconfigured to generate a signal indicative of a performance parameter ofthe hydraulic system; and a controller in communication with the atleast one sensor and configured to: determine at least one of adiagnostic movement and a diagnostic position of at least one of thefluid actuator and the valve required to perform a health check of thehydraulic system; correlate the signal generated only during completionof the diagnostic movement or only when the at least one of the fluidactuator and the valve are in the diagnostic position to a value of theperformance parameter; make a comparison of the value of the performanceparameter to an expected value; and determine a health of the hydraulicsystem based on the comparison.
 2. The hydraulic system of claim 1,wherein the at least one sensor is one of a pressure sensor, a positionsensor, a displacement sensor, and a speed sensor.
 3. The hydraulicsystem of claim 1, wherein the at least one sensor includes at least afirst sensor located to sense a pressure inside a chamber of the fluidactuator.
 4. The hydraulic system of claim 3, wherein the at least onesensor includes at least a second sensor configured to sense a pressuredifferential across the valve.
 5. The hydraulic system of claim 4,further including a pump configured to direct pressurized fluid to thevalve, wherein the at least one sensor includes at least a third sensorconfigured to sense a pressure differential across the pump.
 6. Thehydraulic system of claim 1, wherein the controller is configured toadjust a result of the comparison for an age of the hydraulic system. 7.The hydraulic system of claim 1, wherein the controller is configured todetermine the at least one of the diagnostic movement and the diagnosticposition based on a suspected malfunction of the hydraulic system. 8.The hydraulic system of claim 1, wherein the controller is manuallytriggered to perform the health check of the hydraulic system.
 9. Thehydraulic system of claim 8, wherein the controller is configured toinstruct an operator to cause the at least one of the fluid actuator andthe valve to perform the diagnostic movement or to achieve thediagnostic position.
 10. The hydraulic system of claim 9, wherein thecontroller is further configured to selectively recommend one of threepossible corrective actions based on the health of the hydraulic system.11. The hydraulic system of claim 9, wherein the three possiblecorrective actions include: a first level action, wherein the operatoris instructed to schedule a particular maintenance activity to occur ata next regular service interval; a second level action, wherein theoperator is instructed to perform the particular maintenance activity ata next convenient time; and a third level action, wherein the operatoris instructed to immediately shut down the hydraulic system and performthe particular maintenance activity.
 12. The hydraulic system of claim1, wherein the controller is automatically triggered to perform thehealth check of the hydraulic system based on a sensed performanceparameter of the hydraulic system.
 13. The hydraulic system of claim 12,wherein the controller is configured to automatically cause the at leastone of the fluid actuator and the valve to perform the diagnosticmovement or to achieve the diagnostic position.
 14. The hydraulic systemof claim 13, wherein the controller is further configured toautomatically implement one of three possible corrective actions basedon the health of the hydraulic system.
 15. The hydraulic system of claim9, wherein the three possible corrective actions include: a first levelaction, wherein the controller automatically schedules a particularmaintenance activity to occur at a next regular service interval; asecond level action, Wherein the controller automatically schedules theparticular maintenance activity to occur at a next convenient time; anda third level action, wherein the controller immediately shuts down thehydraulic system and generates a request for the particular maintenanceactivity to be performed before restart of the hydraulic system.
 16. Thehydraulic system of claim 1, wherein the controller is configured tocontinuously perform the health check of the hydraulic system wheneverthe at least one of the fluid actuator and the valve are in performanceof the diagnostic movement or are in the diagnostic position.
 17. Amethod of determining a health of a hydraulic system having a fluidactuator and a valve associated with the fluid actuator, the methodcomprising: generating a signal indicative of a performance parameter ofthe hydraulic system; determining at least one of a diagnostic movementand a diagnostic position of at least one of the fluid actuator and thevalve required for diagnosing the health of the hydraulic system;correlating the signal generated only during completion of thediagnostic movement or only when the at least one of the fluid actuatorand the valve are in the diagnostic position to a value of theperformance parameter; making a comparison of the value of theperformance parameter to an expected value; and determining the healthof the hydraulic system based on the comparison.
 18. The method of claim17, further including adjusting the comparison based on an age of thehydraulic system.
 19. The method of claim 17, wherein determining the atleast one of the diagnostic movement and the diagnostic position of theat least one of the fluid actuator and the valve includes determiningthe at least one of the diagnostic movement and the diagnostic positionof the at least one of the fluid actuator and the valve based on asuspected malfunction of the hydraulic system.
 20. A machine,comprising: a frame; a power source mounted to the frame; a linkagearrangement; a fluid actuator configured to move the linkagearrangement; a pump; a sump; a valve disposed between the fluidactuator, the pump, and the sump; a plurality of sensors configured togenerate signals indicative of performance parameters of the machine;and a controller in communication with the plurality of sensors andconfigured to: receive input indicative of a suspected hydrauliccomponent malfunction; determine at least one of a diagnostic movementand a diagnostic position of at least one of the fluid actuator and thevalve required to performe a health check of the machine based on thesuspected hydraulic component malfunction; correlate the signalsgenerated only during completion of the diagnostic movement or only whenthe at least one of the fluid actuator and the valve are in thediagnostic position to values of the performance parameters; determinean age of the machine; make an age-adjusted comparison of the values ofthe performance parameters to expected values; and determine a health ofthe machine based on the age-adjusted comparison.